1. Technical Field
The present invention relates to a flow assisted-solid phase microextraction/gas chromatography-mass spectrometry (FA-SPME/GC-MS) system and a method for using the FA-SPME/GC-MS in which contacting, desorbing and determining analyte content are carried out consecutively.
2. Description of the Related Art
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.
Chloroethers (CEs) are compounds which contain an ether moiety (R—O—R) and halogen atoms attached to the aryl or alkyl groups. CEs are produced in significant quantities (more than 50 million pounds per year) and are commonly used as solvents in various industrial applications (C. Chiing-Chen, W. Ren-Jang, Y. I.-Chun, L. Chung-Shin, J. Hazard. Mater 172 (2009) 1021; C. Jing-Shan, H. Shang-Da, Talanta 71 (2007) 882; M. Sittig, Handbook of Toxic and Hazardous Chemicals and Carcinogens, third ed., Noyes Public, New Jersey, 1991—each incorporated herein by reference in its entirety). Significant quantities of CEs are produced and utilized in the industry. Generally, CEs are stable and non-biodegradable in aqueous samples.
Bis(2-chloroethyl)ether (BCEE), bis(2-chloroisopropyl) ether (BCIE) and Bis(2-chloroethoxy)methane (BCEM) are a class of CEs frequently found in drinking water and urine (H. Sahng-Da, T. Chun Yi, L. Cheng-Shium, J. Chromatogr. A 769 (1997) 239; R. C. Dressman, J. Fair, E. F. Mcfarren, Environ. Sci. Technol. 11(1977) 719; I. H. Suffet, P. R. Cairo, J. Environ. Sci. Heal. A13 (1978) 117; R. D. Lingg, W. H. Kaylor, S. M. Pyle, M. M. Domino, Envirom. Con. Tox. 11 (1982) 173—each incorporated herein by reference in its entirety). Thus, the release of CEs into the environment is of great concern because of their toxicity and carcinogenicity (J. K. Fawell, S. Hunt, Environmental Toxicology: Organic Pollutants, Wiley, New York, 1988 (Chapter 9); L. Wennrich, W. Engewald, P. Poppb, lnrern J. Environ. Anal. Chem. 73(1998) 31—each incorporated herein by reference in its entirety). The United Sates Environmental Protection Agency (USEPA) and the International Agency for Research on Cancer have classified CEs as a carcinogenic compound category D (Wisconsin Department of Natural Resources Drinking Water & Groundwater Quality Standards/Advisory Levels, March 2011—incorporated herein by reference in its entirety).
The volatility and water solubility of BCEM may result in human exposure by inhalation, ingestion or dermal contact in the course of occupational exposures. The minimum half-life of BCEM in water has been reported to be 2 years (S. R. Black, K. S. Decosta, P. R. Patel, J. M. Mathews, Xenobiotica 37 (2007) 427; W. R. Haag, T. Mill, SRI Project No. 6877-1, Menlo Park, Calif., USA., (1989) 20—each incorporated herein by reference in its entirety) presenting the potential for persistent environmental exposure.
In this regard, different preconcentration methods have been reported for the analysis of CEs in water samples which includes USEPA methods 611 and 625 based on liquid-liquid extraction (LLE). However, LLE procedures require large volumes of hazardous organic solvents and multi-step extractions which are time-consuming and involve the risk of analyte loss in the extraction and concentration processes and not suitable for trace level determination (A. Mousa, C. Basheer, A. R. Al-Arfaj, Talanta 115 (2013) 308—incorporated herein by reference in its entirety). The solid-phase extraction (SPE) is a solvent minimized alternative to the LLE approach, SPE-C8, which was used for CEs. The main problem associated with SPE-C8 is the low selectivity of the retention mechanism of CEs which yielded low recoveries (E. Chladek, R. S. J. Marano, Chromatogr. Sci. 22 (1984) 313.—incorporated herein by reference in its entirety).
In recent years, microextraction techniques for CEs have produced an important development in trace level analyses from various environmental samples. Liquid-phase microextraction (LPME) and solid-phase microextraction (SPME) are alternative microextraction methods for CEs (Y. He, H. K. Lee, Anal. Chem. 69 (1997) 4634; Y. Wang, Y. C. Kwok, Y. He, H. K. Lee, Anal. Chem. 70 (1998) 4610—each incorporated herein by reference in its entirety). LPME is a solvent minimized extraction technique in which CEs are extracted using immiscible organic solvents. The selection of suitable organic solvents for polar analytes and fully automation of LPME are challenging tasks.
Solid-phase microextraction (SPME) is a widely used solvent-free extraction microextraction technique which combines sampling, sample clean-up and pre-concentration into a single step (G. Ouyang, D. Vuckovic, J. Pawliszyn, Chem. Rev., 111(2011), 2784—incorporated herein by reference in its entirety). On the other hand, SPME requires careful calibration for the quantization of trace level analytes. This requires more time (J. Pawliszyn, Ed. Applications of Solid Phase Microextraction; RSC Chromatography Monographs: Cambridge, U.K., 1999—incorporated herein by reference in its entirety). Manual SPME optimization methods allow for human error and the possibility of contamination associated with manual processing (R. Vatinno, D. Vuckovic, C. G. Zambonin, J. Pawliszyn, J. Chromatogr. A 1201, (2008) 215—incorporated herein by reference in its entirety). Automated sample preparation eliminates human intervention in order to improve overall sample analysis efficiency and reliable robustness of the method (D. Vuckovic, Trends Anal. Chem., 45 (2013), 136—incorporated herein by reference in its entirety).
The present disclosure describes an automated flow assisted solid-phase microextraction (FA-SPME) combined with GC-MS in order to quantify CEs in large volume samples. SPME automation has been widely used in various modes such as headspace-SPME, direct immersion-SPME, and different formats which includes thin film-SPME, in-tip-SPME and 96 vial plate-SPME (B. Bojko, E. Cudjoe, G. A. Gomez-Rios, K. Gorynski, R. Jiang, N. Reyes-Garcas, S. Risticevic, E. A. S. Silva, O. Togunde, D. Vuckovic, J. Pawliszyn, Anal. Chim. Acta. 750 (2012) 132; W. Xie, J. Pawliszyn, W. M. Mullett, B. K. Matuszewski, J. Pharm. Biomed. Anal. 45 (2007) 599; D. Vuckovic, X. Zhang, E. Cudjoe, J. Pawliszyn, J. Chromatogr. A, 1217 (2010) 4041). In general, SPME automation has been reported only for small volume samples.